Calculation of Solubility of Organic Compounds in Supercritical CO₂ Based on Quantitative Structure-Activity Relationships

Development of Correlation Equation Using Experimental Variable

Abstract

Quantitative structure-activity relationship (QSAR) correlations were developed for the solubility of organic compounds in supercritical CO₂ at (308K, 20MPa) and (328K, 12.7MPa). To identify the molecular structural variables that control solvation phenomena, we first developed the QSAR correlation of solubility of 32 organic compounds in supercritical CO₂ at (308K, 20MPa) using experimentally and theoretically derivable variables. The experimental variable used was the melting point, and the theoretical variables were molecular orbital basicity and dipole moment. The latter were determined using COSMO-PM3 method. Based on the results at (308K, 20MPa), the QSAR correlation for solubility in supercritical CO₂ at (328K, 12.7MPa) was determined from the solubility data for 16 other compounds in the literature. The QSAR correlation including the melting point and dipole moment as variables dramatically improved the accuracy of the predicted solubility of organic compounds in supercritical CO₂.